diff --git a/src/transforms/remainder.jl b/src/transforms/remainder.jl
index 267b7e1..7ae76e3 100644
--- a/src/transforms/remainder.jl
+++ b/src/transforms/remainder.jl
@@ -10,18 +10,64 @@ and returns a new table with an additional column containing the
 remainder value `xₙ₊₁ = total .- (x₁ + x₂ + ⋯ + xₙ)` If the `total`
 value is not specified, then default to the maximum sum across rows.
 """
-struct Remainder <: Transform end
+struct Remainder <: Transform
+  total::Union{Float64,Nothing}
+end
+
+Remainder() = Remainder(nothing)
 
 isrevertible(::Type{Remainder}) = true
 
-function apply(::Remainder, table)
-  # TODO
+assertions(::Type{Remainder}) = [TT.assert_continuous]
+
+function _cache(transform::Remainder, table)
+  # design matrix
+  X = Tables.matrix(table)
+
+  # find total across rows
+  if !isnothing(transform.total)
+    transform.total
+  else
+    maximum(sum(X, dims=2))
+  end
 end
 
-function revert(::Remainder, newtable, cache)
-  # TODO
+function _apply(transform::Remainder, table, cache)
+  # basic checks
+  for assertion in assertions(transform)
+    assertion(table)
+  end
+
+  # design matrix
+  X = Tables.matrix(table)
+
+  # retrieve the total
+  total = cache
+
+  # make sure that the total is valid
+  @assert all(x -> x ≤ total, sum(X, dims=2)) "the sum for each row must be less than total"
+
+  # original column names
+  names = Tables.columnnames(table)
+
+  # create a column with the remainder
+  S = sum(X, dims=2)
+  Z = [X (total .- S)]
+
+  # table with the new column
+  rname = Symbol("total_minus_", join(string.(names)))
+  names = (names..., rname)
+  𝒯 = (; zip(names, eachcol(Z))...)
+  newtable = 𝒯 |> Tables.materializer(table)
+
+  newtable, total
 end
 
-function reapply(::Remainder, table, cache)
-  # TODO
+apply(transform::Remainder, table) = _apply(transform, table, _cache(transform, table))
+
+function revert(::Remainder, newtable, cache)
+  names = Tables.columnnames(newtable)
+  TT.Reject(last(names))(newtable)
 end
+
+reapply(transform::Remainder, table, cache) = _apply(transform, table, cache)
\ No newline at end of file
diff --git a/test/transforms.jl b/test/transforms.jl
index c523bec..c6c3026 100644
--- a/test/transforms.jl
+++ b/test/transforms.jl
@@ -36,4 +36,20 @@
   tcls = revert(Closure(), n, c)
   @test Tables.matrix(n) ≈ [0.2 0.4 0.4; 0.66 0.22 0.12; 0.00 0.02 0.98;]
   @test Tables.matrix(tcls) ≈ Tables.matrix(t)
+
+  # Tests for Remainder
+  t = (a=Float64[2,66,0], b=Float64[4,22,2], c=Float64[4,12,98])
+  n, c = apply(Remainder(), t)
+  trem = revert(Remainder(), n, c)
+  Xt = Tables.matrix(t)
+  Xn = Tables.matrix(n)
+  @test Xn[:, 1:end-1] == Xt
+  @test all(x -> 0 ≤ x ≤ c, Xn[:, end])
+  @test n    |> Tables.columnnames == (:a, :b, :c, :total_minus_abc)
+  @test trem |> Tables.columnnames == (:a, :b, :c)
+
+  t = (a=Float64[1,10,0], b=Float64[1,5,0], c=Float64[4,2,1])
+  n, c = reapply(Remainder(), t, c)
+  Xn = Tables.matrix(n)
+  @test all(x -> 0 ≤ x ≤ c, Xn[:, end])
 end