Let $X$
X
be a linear diffusion taking values in $(\ell ,r)$
(
ℓ
,
r
)
and consider the standard Euler scheme to compute an approximation to $\mathbb{E}[g(X_{T}){\mathbf{1}}_{\{T<\zeta \}}]$
E
[
g
(
X
T
)
1
{
T
<
ζ
}
]
for a given function $g$
g
and a deterministic $T$
T
, where $\zeta =\inf \{t\geq 0: X_{t} \notin (\ell ,r)\}$
ζ
=
inf
{
t
≥
0
:
X
t
∉
(
ℓ
,
r
)
}
. It is well known since Gobet (Stoch. Process. Appl. 87:167–197, 2000) that the presence of killing introduces a loss of accuracy and reduces the weak convergence rate to $1/\sqrt{N}$
1
/
N
with $N$
N
being the number of discretisations. We introduce a drift-implicit Euler method to bring the convergence rate back to $1/N$
1
/
N
, i.e., the optimal rate in the absence of killing, using the theory of recurrent transformations developed in Çetin (Ann. Appl. Probab. 28:3102–3151, 2018). Although the current setup assumes a one-dimensional setting, multidimensional extension is within reach as soon as a systematic treatment of recurrent transformations is available in higher dimensions.